Field of the Invention
The present invention relates to a boot used in an optical connector ferrule for forming a muticore collective connector, for example, Mechanically-Transferable-splicing-Connector (hereinafter, refer to as MT connector), Multifiber-Push-on-Connector (hereinafter, refer to as MT connector), and Multifiber-Push-on-Connector (hereinafter, refer to as MPO connector), which is used for connecting optical fiber core wires and optical fiber tape (ribbon fiber) core wires.
Description of the Conventional Art
As a collector for collectively connecting with low loss SM type optical fiber single core wires and tape core wires, there has been conventionally used a multicore collective connector which can connect the optical fibers efficiently with a high density, with development a high density multicore cable which single mode type optical fiber tapes (ribbon fibers), for example, having four cores, eight cores and twelve cores. The connecting method is a method of positioning and fitting ferrules in which the multicore optical fibers are positioned and fixed with two guide pins, and the connector is called as an MT connector since the connector can be applied to a mechanical high-speed switching in addition to the collective connection of the optical fiber tapes, and has been in recent years put to practical use as a connector for connecting the optical fiber tapes having four cores, eight cores and twelve cores of an access series multicore cable.
Further, in recent years, an MPO connector has been put to practical used, the MPO connector being structured such as to be easily detachable according to a push-pull operation as a multicore collective connector having twenty four cores and seventy two cores further provided for connecting super multicore cables.
Specifically, as disclosed in patent document 1, there has been known a connector having a ferrule of an optical connector of a system which is provided with a fiber hole in a front end portion and is positioned with the other end ferrule by a fitting pin inserted to a guide pin hole, the ferrule being constructed by a connection end portion which is a part including the fiber hole and the guide pin hole, and a main body rear portion which is the other part than the connection end portion, and the main body rear portion being the portion except the connection end portion, and including an internal space in an inner portion, and the internal space being constructed by a coating insertion portion and a boot insertion portion.
More specifically, the optical connector in the patent document 1 mentioned above is provided with a pair of right and left positioning guide pin insertion holes 102 which pass through from a front end surface to a rear end surface of a ferrule main body 100 as well as being provided with a window portion 101 for filling an adhesive agent on an upper surface of the ferrule main body 100, and is structured such that a plurality of optical fiber core wire insertion holes 103 are provided side by side between both guide pin insertion holes 102 in the front end surface, as shown in FIGS. 13A and 13B. Further, the connector is structured such that a rear end surface of the ferrule main body 100 is provided with a rectangular opening shaped insertion opening portion 104 which inserts a rectangular tubular boot 106 (refer to FIGS. 12A and 12B) thereto and supports, and a rear end side of the ferrule main body 100 is provided with a collar portion 105 which protrudes outward from an outer peripheral surface of the ferrule main body 100.
Accordingly, the rectangular tubular boot 106 is formed into a flat surface in its upper and lower, and right and left outer wall surfaces, as shown in FIGS. 12A and 12B. Further, a pair of wide front opening portions 107a are formed in the front end portion of the boot 106, and a vertical width and a lateral width of the front opening 107a are set to magnitudes which correspond to a thickness and a lateral width of a single mode type ribbon fiber (optical fiber tape) T. A pair of upper and lower wide ribbon fiber insertion portions 107b are formed in the rear end portion of the boot 106, and a vertical width of the ribbon fiber insertion portions 197b is set to be somewhat smaller than a vertical width of the front opening portion 107a in the front end portion at such a degree that only a 12-core optical fiber core wire F protruding out of the front end portion of the single mode type ribbon fiber (optical fiber tape) T can protrudes outward.
Further, in the case of connecting two multicore optical cables each having a plurality of optical fibers, the optical cables are connected by inserting connector plugs installed in the respective multicore optical cables into a relay adapter. For example, in the optical fiber multicore connector, the MPO connectors having the MT ferrules built-in are inserted into the relay adapter and are fixed so that ground surfaces of the MT ferrules come into contact in parallel in the same manner as the case of the MT connector, so that the multicore connectors are connected via the relay adapter.
Conventionally, the MT type optical connector is structured, as shown in FIG. 14, such that a pin holder H is arranged so as to hold a rectangular tubular boot 106 protruding to a rear end surface of a collar portion 105 protruding outward from an outer peripheral surface of a ferrule main body 100, the pin holder H being provided for retaining a positioning pin P and formed into a C-shaped frame, and always applies a forward pressing force to the ferrule main body 100 by an elliptic spring SP which is installed astride the boot 106 and the pin holder H from a rear side in a pressure contact manner.